Add martindelille to code owners

[MartinDelille]

I discovered the github code owner feature that could be useful to improve the review process which is currently done by manually pinging the language team.

If I understand correctly, this changes should automatically ping me when the path mentioned in the CODEOWNERS file are modified in a PR.

I of course don't claim any ownership here but just want to improve the review process. If it seems suitable we could extends this to other contributors.

It would close a preview try to simplify review project (close #10623).

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  For Windows users, please run the script in Git BASH.
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

[MartinDelille]

ping @generator-core-team @jimschubert @openapitools/generator-core-team @wing328

[wing328]

OK. Let's give it a try 👍

[MartinDelille]

It won't work since codeowners need write access.